1. Field of the invention
This invention relates to improvements in a sealing device and more particularly to a sealing device for use in the mating surfaces of blocks or shell members, such as cylinder blocks in a compressor.
2. Description of the Prior Art
FIG. 1 shows a conventional, swash-plate type compressor, in which the walls of cylinder blocks 1 and 2 form shell members of the compressor. In this compressor, an O-ring device 3 is provided in one of the mating end surfaces of the cylinder blocks 1, 2, thereby providing a seal therebetween. In this respcect, it has been a general practice that, as shown in FIG. 4, an annular O-ring groove 4 is provided in one of the mating end surfaces of the cylinder blocks 1, 2 along the circumference thereof, while an O-ring 5 has a transverse cross-sectional area giving a diameter greater than the depth of the O-ring groove 4 and is fitted in the O-ring groove 4. Then, the mating end surfaces of the cylinder blocks 1, 2 are brought into a mated realtion, so that the O-ring is compressed by the mating surface of another counterpart cylinder block with the cooperation of the walls of the O-ring groove 4, thereby providing a good seal for the shell members or cylinder blocks of a compressor. According to the prior art sealing device of the type described, there may be established complete seals between the O-ring 5 and the bottom of the O-ring groove 4, and between the O-ring 5 and the mating surface of a counterpart shell member or cylinder block 2, while the portions of the mating surfaces, other than the O-ring groove 4, provide incomplete metal-to metal seals, with the result that a void 6 in the O-ring groove 4, as shown, is maintained in an incompletely sealed condition to the exterior of the compressor, while a void 7 therein is maintained in an incompletely sealed condition to the inner cavities of the cylinder blocks.
In addition, it has been also a general practice, upon the assembly of a compressor, to apply lubricating oil to the contacting surfaces of respective parts or components so as to improve the slidability of the parts in a compressor as well as the sealing performance of the O-ring and the like, and then to remove the lubricating oil clinging to the surfaces of the parts in the compressor therefrom, after the assembly thereof, with the aid of a cleaning liquid, followed by the delivery to the succeeding step of the manufacture of the compressor, such as a packing step. However, the aforenoted prior art compressors suffer from a shortcoming stemming from lubricating oil which is trapped in the void 6 in the O-ring groove, after the assembly thereof. More specifically, it offers a considerable difficulty for a cleaning liquid to pass through a mating plane or portion 8 of the mating surfaces of the cylinder blocks, which portion is positioned radially outwardly of the O-ring groove 4, because the mating portion 8 provides a metal-to metal seal, which is not complete from a viewpoint of an ideal sealing performance, with the result that the lubricating oil trapped or residual in the void 6 can hardly be removed with a cleaning liquid, so the lubricating oil dwells intact in the void 6, even after the delivery of a product, i.e., a completed compressor, following a packing step. However, as the time goes on (for instance, after the lapse of a relatively long period of time, such as several days), the lubricating oil trapped in the void 6 exudes past the aforenoted mating portion 8 which provides an incomplete seal, thereby staining a package or the surface of a compressor, leading to a critical defect from the viewpoint of quality control.